Re: Table object

Philipp <>
Fri, 17 Jul 2009 03:05:50 -0700 (PDT)
On Jul 17, 11:37 am, Alessio Stalla <> wrote:

On Jul 17, 11:30 am, Philipp <> wrote:

I'm looking for a collection which behaves like a two column table
(ordered key - value pairs, key not unique). Is there such a thing
either in the JRE or Apache collections?

A list of tuples?

class Tuple<K, V> {
  K key;
  V value;


It's not exactly clear what you want: "ordered" pairs - ordered how?
By order of insertion, or by Comparable/Comparator?

key - value pairs: do you need collection.get(key) ==> value?
collection.indexOf(key)? etc.

You could have to subclass some java.util.*List class.

Yes sorry I forgot to mention that I would like to have it implement
Map. Thus have something like a Collection which at the same time
implement List and Map (which is not possible).

I did produce such a thing myself, but maybe I overlooked a more
standard interface and implementation.

// comments stripped for brevity
public interface TableMap extends Map {

  // from List
  public Object set(int index, Object value);
  public Object get(int index);
  public Object remove(int index);

  // all methods from Map but in particular:
  /** Returns the first Object for that key */
  public Object get(Object key);
  /** Removes the first entry for that key */
  public Object remove(Object key);
  /** Throws UnsupportedOperationException */
  public Set entrySet();

  // additionally
  public Object getKey(int index);
  public void removeAll(Object key);
  public List keyList();
  public List valueList();

On second thought, this seems way too strange to be in any standard
lib. I'll just have to stick with my implementation.

Thanks Phil

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